Heating apparatus and heating furnace

ABSTRACT

A heating apparatus, which can stably fix a heater and be easily produced, includes a heat insulating material and an electric heater embedded in the surface or near the surface of the heat insulating material . At least one hook extends from the electric heater into the heat insulating material. The heat insulating material is formed of ceramic fibers and a binder binding the ceramic fibers, and is integrally molded with the electric heater having the hook.

TECHNICAL FIELD

The present invention relates to a heating apparatus for heating aheating furnace, and a heating furnace using the heating apparatus.

BACKGROUND ART

Conventionally, an electric heater used in a high-temperature heatingfurnace at 700 degree C. or more, particularly 1,000 degree C. or more,is fixed to the surface of a heat insulating material by a staple or alocking pin so as to enable direct heating of the inside of the furnace.

More specifically, as shown in FIG. 9, in the heating apparatus 90 ofthe prior art, in order to fix an electric heater 2 on the surface of aheat insulating material, a linear heater 2 is disposed in a meanderconfiguration on the surface of a heat insulating material 1, and thenceramic-made pins 3 are inserted into the heat insulating material 1 atthe curved portions, or metal-made staples 5 are inserted into the heatinsulating material 1 so as to clip the linear heater 2. In theembodiment of FIG. 9, end parts of the linear heater 2 are connected toelectrode terminals 4, and the electrode terminals 4 penetrate a throughhole provided in the heat insulating material 1 to communicate with theback side.

Such an electric heater has a problem that deformation or saggingreadily occurs at a high temperature other than at the fixed points, orrepetition of heating/cooling is likely to cause a drop-off. Further,Such an electric heater has not only a problem that the life is short,but also a problem that pin driving or staple driving imposes a largeload on the manufacturing process.

In order to solve this problem, a method of fixing an electric heater byembedding or inserting a part of the electric heater into a heatinsulating material of felt-formed fiber has been proposed (PatentDocuments 1 and 2).

However, in such a method, the stability of the electric heater is stillinsufficient, or there is room for improvement in terms of the load onthe manufacture thereof.

CITATION LIST Patent Literature PTL 1: JP2002-372381A PTL 2:JP2005-129273A SUMMARY OF INVENTION Solution to Problem

Under these circumstances, an object of the present invention is toprovide a heating apparatus which solves the problems in conventionaltechniques, and a heating furnace provided with the heating apparatus.Means to Solve the Problems

In order to attain the above-described object, the present inventionprovides the followings.

<1> A heating apparatus,

wherein said heating apparatus comprises a heat insulating material, anelectric heater embedded in the surface or near the surface of said heatinsulating material, and a hook extending from said electric heater intosaid heat insulating material,

wherein said heat insulating material is formed of ceramic fibers and abinder binding the ceramic fibers, and is integrally molded with saidelectric heater having said hook.

<2> The heating apparatus according to the aspect <1> above, wherein theapparatus further comprises an electrically insulating support memberembedded in said heat insulating material, and said electricallyinsulating support member supports said hook in said heat insulatingmaterial.

<3> The heating apparatus according to the aspect <1> or <2> above,wherein said electric heater is formed in a meander configuration byproviding alternate slits in a metal plate from both side edges thereof,the portion forming said slit of said metal plate is bent from saidmetal plate to form a plurality of alternately opposing hooks.

<4> The heating apparatus according to the aspect <3> above, whereinsaid alternately opposing hooks in rows on both sides are supported byone electrically insulating support member.

<5> The heating apparatus according to the aspect <3> above, whereinsaid alternately opposing hooks in each row are supported by each ofseparate insulating support members.

<6> The heating apparatus according to any one of the aspects <1> to <5>above, wherein said electric heater comprises a plurality of metalplates formed in a meander configuration, and said plurality of metalplates in a meander configuration are inter-connected by welding.

<7> The heating apparatus according to any one of the aspects <1> to <6>above, wherein the surface of said heater is flush with the surface ofsaid heat insulating material.

<8> The heating apparatus according to any one of the aspects <1> to <7>above, wherein said electrically insulating support member is a hollowbody, the apparatus further comprises a heat-resistant memberpenetrating through the hollow part of the said electrically insulatingsupport member, and said heat-resistant member extends outside of saidheat insulating material.

<9> The heating apparatus according to the aspect <9> above, whereinsaid heat-resistant member is made of ceramic or a metal.

<10> A heating furnace having the heating apparatus according to any oneof the aspects <1> to <9> above.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] A perspective view of the first embodiment of the heatingapparatus of the present invention, which is observed from the heaterside.

[FIG. 2] A perspective view of the heater used in the first embodimentof the heating apparatus of the present invention, which is observedfrom the backside of the heater.

[FIG. 3] A transparent perspective view of the second embodiment of theheating apparatus of the present invention, which is observed from theopposite side from the heater.

[FIG. 4] (a) A transparent perspective view and (b) a perspective viewof the second embodiment of the heating apparatus of the presentinvention, which is observed from the heater side.

[FIG. 5] A perspective view of the heater used in the second embodimentof the heating apparatus of the present invention, which is observedfrom (a) the heater side and (b) the backside of the heater.

[FIG. 6] A transparent perspective view of the third embodiment of theheating apparatus of the present invention, which is observed from theopposite side from the heater.

[FIG. 7] A transparent perspective view of the fourth embodiment of theheating apparatus of the present invention, which is used for acylindrical muffle furnace and observed from the heater side.

[FIG. 8] A transparent perspective view of the fifth embodiment of theheating apparatus of the present invention, which is used for acylindrical muffle furnace and observed from the heater side.

[FIG. 9] A perspective view of the conventional heating apparatus, whichis observed from the heater side.

MODE FOR CARRYING OUT THE INVENTION

<<Heating Apparatus>>

The heating apparatus of the present invention comprises a heatinsulating material, an electric heater embedded in the surface or nearthe surface of the heat insulating material, and a hook extending fromthe electric heater into the heat insulating material. The heatinsulating material is formed of ceramic fibers and a binder binding theceramic fibers, and is integrally molded with the electric heater havingthe hook.

According to the heating apparatus of the present invention, deformationand drop-off of the heater can be prevented with an uncomplicatedmanufacture process, since the heat insulating material is integrallymolded with the electric heater so as to the hook extends into the heatinsulating material, i.e. since, during the molding of the heatinsulating material, the insulating material and the electric heater isbonded and integrated.

Incidentally, in order to enhance the effect of anchoring the hook tothe heat insulating material, it is preferable to increase the surfacearea of the parallelly bent portion at the end of the hook or toincrease the number of hooks.

Further, according to the heating apparatus of the present invention,the distance between adjacent heaters can be decreased, and therebyin-plane density of the electric heater can be increased, sincedeformation of the electric heater can be prevented.

Further, according to the heating apparatus of the present invention,the heat insulating material panel can be made thin and/or small, sincea margin for inserting pins or staples is not necessary.

The surface of the electric heater may be flush with the surface of theheat insulating material, may be embedded below the surface heatinsulating material, or may be protruded from the surface of the heatinsulating material.

If the surface of the electric heater is flush with the surface of theheat insulating material, or is embedded below the surface heatinsulating material, the surface of the electric heater is not protrudedfrom the surface of the heat insulating material, so that theto-be-heated body can be put close to the electric heater surface,leading to improvement of uniform heating characteristics.

The heating apparatus of the present invention may be a flatpanel-shaped one, or one for a cylindrical muffle furnace.

The heating apparatus of the present invention can be produced, e.g. bya cast molding method, vacuum molding method, or the like, and a vacuummolding method is preferred.

When the heating apparatus of the present invention is produced with avacuum method, for example, a suction device connected to a vacuum pumpand a forming die disposed thereon are placed in a tank, and a slurryobtained by dissolving or dispersing ceramic fibers in a binder ishoused in the tank. The top of the suction device connected to a vacuumpump has a net shape, and therefore the inside of the forming diedisposed thereon can be vacuum-suctioned. In the state where theelectric heater having a hook, and the optional electrically insulatingsupport members are disposed at predetermined positions in the formingdie, vacuum is applied into the forming die through the vacuum pump andthe suction device, as a result, the ceramic fibers and binder aresuctioned and deposited on the net-shaped bottom in the forming die tobe formed into the shape of the heat insulating material.

At this time, the ceramic fibers and binder forming the heat insulatingmaterial are integrally molded so as to arrange the electric heater asthe bottom and include (embed) the electric heater, the hook and theelectrically insulating support members. By taking the heat insulatingmaterial molded out of the tank and drying it, the binder binds theceramic fibers, and thus a heat insulating material including(embedding) the electric heater, and the electrically insulating supportmembers is integrally molded.

In the heat insulating material thus obtained by an integral moldingmethod, the bottom is flush with the surface of the electric heater, andbasically, the electric heater having the hook are put into closecontact with the heat insulating material, and the optional electricallyinsulating support members are put into close contact with the heatinsulating material.

Incidentally, although the slurry is sometimes thinly attached to thesurface of the electric heater, the slurry may be left attached as itis, or may be removed to completely expose the electric heater. It isalso possible to intentionally embed the surface of the electric heater.

<Heat Insulating Material>

The heat insulating material is a molded body comprising ceramic fibersand a binder binding the ceramic fibers. Alumina-silica fiber can beused as a ceramic fiber, and colloidal silica can be used as the binder.

Further, for molding of the heat insulating material, slurry comprisingwater as a solvent, as well as the ceramic fibers and the binder, can beused.

<Electric Heater>

The electric heater used in the heating apparatus of the presentinvention can have any configuration. For example, the electric heateris formed in a meander configuration by providing alternate slits in ametal plate from both side edges thereof, the portion forming the slitof the metal plate is bent from the metal plate to form a plurality ofalternately opposing hooks.

If the hook is formed in this way by utilizing an extra portion (slitportion) of the metal plate forming the electric heater of a meanderconfiguration, an extra material for forming the hook is not necessary.Further, in this case, a hook is formed in each turn of the meanderingpath, leading to an effect that the electric heater can be stably held.

The alternately opposing hooks in rows on both sides may be supported byone electrically insulating support member, or the alternately opposinghooks in each row may be supported by each of separate insulatingsupport members, i.e. may be supported by total two insulating supportmembers.

The electric heater may comprise a plurality of metal plates formed in ameander configuration, and the plurality of metal plates in a meanderconfiguration are inter-connected by welding, optionally via a metalmember of the same material as the electric heater. A plurality of metalplates formed in a meander configuration may be formed of a single metalplate.

As the electric heater, a metal-made heater is preferred, and forhigh-temperature heating, for example, NiCr, FeCrAl, Mo and W may beused. Particularly, FeCrAl allowing for high-temperature heating andexcellent also in the oxidation resistance is preferred.

<Electrically Insulating Support Member>

The heating apparatus of the present invention further may comprise anelectrically insulating support member embedded in the heat insulatingmaterial, and the electrically insulating support member may support thehook in the heat insulating material. In other words, the electricallyinsulating support member is a member for holding the hook of theelectric heater to stably hold the electric heater.

Drop-off of the electric heater can be further prevented by supportingthe hook of the electric heater by the electrically insulating supportmember.

The shape of the electrically insulating support member is not limited,as far as the member itself is embedded in the heat insulating materialand holds the hook, and thereby stabilize the holding of the electricheater in comparison with the case wherein the electric heater is heldonly by the hook.

The electrically insulating support member having a rod shape is simpleand preferred in order to hold a hook of the electric heater, e.g. tohold a series of hooks formed in the slit portions of the electricheater in a meander configuration. The shape and size may be the same ordifferent between the electrically insulating support members holdingtwo hook rows.

In the case where the hook is thus held by an electrically insulatingsupport member, even when the area of the parallelly bent portion at theend of the hook is not increased, the hook, and in turn, the electricheater can be firmly held by the electrically insulating support member.

The electrically insulating support member is composed of anelectrically insulating material. In view of heat resistance, theelectrically insulating support member is preferably composed of aceramic material such as alumina, mullite, sillimanite, zirconia,magnesia and silicon nitride is preferred.

The electrically insulating support members may be optionally formed ina hollow shape, and particularly a hollow tubular shape, whereby aheat-resistant member can be passed through it as described below.

<Heat-Resistant Member>

The electrically insulating support members may be optionally formed ina hollow shape, and particularly a hollow tubular shape, whereby aheat-resistant member can be passed through the hollow part to theoutside of the heat insulating material.

By using the heat-resistant member, particularly rod-shapedheat-resistant member, the heating apparatus can be easily supported,and particularly can be easily held or fixed.

The heat-resistant ceramic may be made of ceramic or metal. The ceramicmay be alumina, silicon nitride, etc. which are electricallynonconductive, or may be electrically conductive silicon carbide. Themetal may be the same material as the electric heater.

The heating apparatus of the present invention is described belowregarding the first to fifth embodiment, but the present invention isnot limited thereto.

First Embodiment

The first embodiment of the heating apparatus 10 of the presentinvention is described in FIGS. 1 and 2.

More specifically, FIG. 1 is a perspective view of the first embodimentof the heating apparatus of the present invention, which is observedfrom the heater side; and FIG. 2 is a perspective view of the heaterused in the first embodiment of the heating apparatus of the presentinvention, which is observed from the backside of the heater.

As illustrated in FIGS. 1 and 2, in the heating apparatus 10, a part ofan electric heater 12 is formed as a hook 13 extending toward the insideof a heat insulating material 11, and the electric heater 12 is integralmolded with the heat insulating material 11. To end parts of theelectric heater 12, electrode terminals 14 are connected.

The hook 13 of the electric heater 12 is formed to extend toward theinside of the heat insulating material 11 at the time of formation ofthe electric heater 12 in a meander configuration. In this heatingapparatus 10, the heat insulating material 11 is molded integrally withthe electric heater 12 having the hook 13, such that the heater 12having the hook 13 is embed in the heat insulating material. The hook 13not only extends from the electric heater 12 toward the inside of theheat insulating material 11, but also is bent at its end part in thedirection parallel to the electric heater 12, and moreover, is moldedintegrally with the heat insulating material 11, and therefore the hook13 is firmly fixed in the heat insulating material 11 and does noteasily come off.

Furthermore, in the heating apparatus 10 of the present invention, theelectric heater 12 is also molded integrally with the heat insulatingmaterial 11, and therefore is directly embedded and fixed in the heatinsulating material 11, leading to a stabilization effect.

In addition, the electric heater 12 is flush with the surface of theheat insulating material 11 and is not protruded, so that a to-be-heatedbody can be disposed in the heating furnace to come close to theelectric heater and the uniform heating characteristics can be improved.

Second Embodiment

The second embodiment of the heating apparatus 20 of the presentinvention is described in FIGS. 3 to 5.

More specifically, FIG. 3 is a transparent perspective view of thesecond embodiment of the heating apparatus of the present invention,which is observed from the opposite side from the heater; FIG. 4 is (a)A transparent perspective view and (b) a perspective view of the secondembodiment of the heating apparatus of the present invention, which isobserved from the heater side; and FIG. 5 is a perspective view of theheater used in the second embodiment of the heating apparatus of thepresent invention, which is observed from (a) the heater side and (b)the backside of the heater.

In the heating apparatus 20, a heat insulating material 21, an electricheater 22 including a hook 23 a and 23 b, and electrically insulatingsupport members 24 and 25 are integrally molded in the form that thehooks 23 extending from the electric heater 22 embrace the electricallyinsulating support members 24 and 25.

The electric heater 22 is shaped as a belt-like heater in a meanderconfiguration by alternately forming slits from both side edges, and themetal portion forming the slit is bent to form hooks 23 a and 23 brespectively on both edge sides of the metal plate.

In this embodiment, two metal plates are used, each metal plate formingan electric heater in a meander configuration, and since these metalplates are usually inter-connected by welding through a metal member 27formed of the same material as the electric heater, the material is lesswasted.

Each of two hook rows 23 a and 23 b formed respectively on both edgesides of each metal plate of the embodiment is held by one electricallyinsulating support member 24 or 25. In this way, two hook rows 23 a and23 b in the width direction of the electric heater 22 are held by twoelectrically insulating support members 24 and 25, whereby there isproduced an effect that the electric heater 22 is more stably held alsoin the width direction.

In this embodiment, one electrically insulating support member 24 isformed in a hollow tubular shape, whereby a rod-shaped heat-resistantceramic- or metal-made member 26 can be passed through the hollow part.Outside of the heat insulating material 21, the rod-shapedheat-resistant member serves as means for holding or fixing the heatingapparatus 20 in a heating furnace.

Third Embodiment

The third embodiment of the heating apparatus 30 of the presentinvention is described in FIGS. 6. FIG. 6 is a transparent perspectiveview of the third embodiment of the heating apparatus of the presentinvention, which is observed from the opposite side from the heater.

This embodiment uses the electric heater 22 formed in a meanderconfiguration from one metal plate, and one electrically insulatingsupport member of hollow tubular shape is embraced by the hooks 23 a and23 b in two rows extending from the electric heater 22.

Forth Embodiment

The forth embodiment of the heating apparatus 40 of the presentinvention is described in FIGS. 7. FIG. 7 is a transparent perspectiveview of the fourth embodiment of the heating apparatus of the presentinvention, which is used for a cylindrical muffle furnace and observedfrom the heater side.

In this embodiment, only one electrically insulating support member 24is used for one electric heater 22, and thus the cost can be reduced.However, in view of stability, two electrically insulating supportmembers 24 can be used, as described above.

Fifth Embodiment

The fifth embodiment of the heating apparatus 50 of the presentinvention is described in FIGS. 8. FIG. 8 is a transparent perspectiveview of the fifth embodiment of the heating apparatus of the presentinvention, which is used for a cylindrical muffle furnace and observedfrom the heater side.

This embodiment is the same cylindrical muffle furnace as the forthembodiment illustrated in FIG. 7, but the bending direction of theelectric heater differs from the forth embodiment illustrated in FIG. 7by 90 degree. In this embodiment, the hook 23 extending from theelectric heater 22 is not held by an electrically insulating supportmember 24, but may be held by an electrically insulating support member24.

<<Heating Furnace>>

A heating furnace, for example cylindrical muffle furnace can beconstructed using the heating apparatus of the present invention by aknown method.

1. A heating apparatus, comprising: a heat insulating material having asurface; an electric heater embedded in the surface or near the surfaceof said heat insulating material; and a hook extending from saidelectric heater into said heat insulating material, wherein said heatinsulating material is formed of ceramic fibers and a binder binding theceramic fibers, and is integrally molded with said electric heaterhaving said hook.
 2. The heating apparatus according to claim 1, furthercomprising an electrically insulating support member embedded in saidheat insulating material, wherein said electrically insulating supportmember supports said hook in said heat insulating material.
 3. Theheating apparatus according to claim 1, wherein said electric heater isformed in a meander configuration by providing alternate slits in ametal plate from both side edges thereof, the portion forming each ofsaid slits of said metal plate is bent from said metal plate to form aplurality of alternately opposing hooks.
 4. The heating apparatusaccording to claim 3, wherein said alternately opposing hooks in rows onboth sides are supported by one electrically insulating support member.5. The heating apparatus according to claim 3, wherein said alternatelyopposing hooks in each row are supported by each of the separateelectrically insulating support members.
 6. The heating apparatusaccording to claim 1, wherein said electric heater includes a pluralityof metal plates formed in a meander configuration, wherein saidplurality of metal plates in the meander configuration areinterconnected by welding.
 7. The heating apparatus according to claim1, wherein a surface of said heater is flush with the surface of saidheat insulating material.
 8. The heating apparatus according claim 1,wherein said electrically insulating support member is a hollow body,the apparatus further comprising a heat-resistant member penetratingthrough the hollow part of the electrically insulating support member,wherein said heat-resistant member extends outside of said heatinsulating material.
 9. The heating apparatus according to claim 8,wherein said heat-resistant member is made of ceramic or a metal.
 10. Aheating furnace having the heating apparatus according to claim 2.